How do I draw shear and moment diagrams for a beam?

[jd747]

I'm not quite sure how to do this. I posted the diagram at my web site...the question is also there, but I typed it here just to give you an idea of what it is about. Thanks! The website:

http://www.geocities.com/jessparker502/


For this problem establish the x-axis with the origin at the left side of the beam and obtain the internal shear and moment as a function of x. Use the results to plot the shear and moment diagrams.

Draw the shear and moment diagrams for the beam (a) in terms of the parameters shown; (b) set p = 600lb, a = 5ft, b=7ft

 

[FredGarvin]

The shear diagram will look like two opposing rectangles, one on top of the axis, the other underneath. The shear forces will be equivilent to the reaction forces at each support, Pb/L on the left side and -Pa/L on the right. The transition between the two will be a vertical line at the point of load application.

The moment diagram will be a triangle with the max equivilent to Pab/L occurring at the point of load application.

This is doable if you start with the statics of the beam. Work out the reaction forces at each end. You could also do a search on shear/moment diagrams. They are printed quite often.

 

[sir-pinski]

, c = 3ft.


To draw shear and moment diagrams for a beam, follow these steps:

1. Identify the supports and reactions: Determine the type of supports and the reactions at each support. This information is important to determine the appropriate equations to use for calculating the shear and moment at different points along the beam.

2. Establish the x-axis: Draw a horizontal line to represent the beam and mark the left end as the origin. This will serve as the x-axis for the diagrams.

3. Determine the internal shear and moment: Use the equations for shear and moment at a point in a beam to calculate the values at different points along the beam. This will require solving for the reactions and applying the appropriate equations based on the supports and loading conditions.

4. Plot the shear diagram: On the x-axis, mark the points where the shear changes sign or magnitude. Then plot the values of shear at each point using a scale that is appropriate for the beam. Connect the points with straight lines to obtain the shear diagram.

5. Plot the moment diagram: On the same x-axis, mark the points where the moment changes sign or magnitude. Then plot the values of moment at each point using a scale that is appropriate for the beam. Connect the points with curved lines to obtain the moment diagram.

6. Label the diagrams: Label the diagrams with the corresponding values of shear and moment at each point. Also, label the locations of the supports and any points of interest such as points of zero shear or maximum/minimum moments.

In the case of the diagram provided on the website, you would need to use the equations for shear and moment at a point in a beam with a distributed load to calculate the values at different points along the beam. Once you have these values, follow the steps above to plot the shear and moment diagrams. If you are unsure about the equations to use or the calculations involved, it may be helpful to consult a textbook or seek assistance from a tutor or professor.